Modelling with AutoCAD 2002 Episode 8 ppt

9 Select the revolve icon from the solids toolbar and: a) objects: select the polyline outline then right-click b) axis of revolution: X axis c) angle of revolution: 250 d) the revolved effect will be as fig(b). Observe then undo 10 At the command line enter REVOLVE <R> and: a) objects: select polyline then right-click b) axis of revolution: enter Y <R> c) angle of revolution: 360 d) the result will be as fig(c) – pan needed? e) observe then undo the revolved effect 11 Finally revolve the polyline: a) about the Y axis b) with a 300 angle of revolution – fig(d) 10 Shade, 3D orbit, etc. then save if required This completes the swept primitive exercises. Plotting multiple viewport layouts with hide To obtain a plot of a multiple layout with hide, the user needs the use the MVIEW command. To demonstrate this command: 1 Open any multiple viewport drawing, e.g. the splined shaft example 2 Enter paper space 3 At the command line enter MVIEW <R> and: prompt Specify corner of viewport or [various options] enter H <R> – the hideplot option prompt Hidden line removal for plotting [ON/OFF] enter ON <R> prompt Select objects respond pick the borders of all viewports which have to have hidden line removal then right-click 4 The command line is returned 5 Proceed with the normal plot sequence, but ensure that the Hide Plot option is NOT ACTIVE (i.e. no tick) 6 This procedure should be used at all times when multi-viewport plots are required with hidden line removal The swept solid primitives 203 modelling with AutoCAD.qxd 17/06/2002 15:41 Page 203 Summary 1 Swept solids are obtained with the extrude and revolve commands 2 The two commands can be activated: a) by icon selection from the Solids toolbar b) from the command line with Draw-Solids c) by entering EXTRUDE and REVOLVE at the command line 3 Very complex models can be obtained from simple shapes 4 Only certain ‘shapes’ can be extruded/revolved. These are closed polylines, circles, ellipses, polygons, closed splines and regions (more on this in a later chapter) 5 Objects can be extruded: a) to a specified height b) with/without a taper angle c) along a path curve 6 The extruded height is in the Z direction and can be positive or negative 7 The taper angle can be positive or negative 8 Objects can be revolved: a) about the X and Y axes b) about an object c) by specifying two points on the axis of revolution 9 The angle of revolution can be full (360) or partial. Assignment During the excavation of the ancient city of CADOPOLIS, the intrepid diggers uncovered two artefacts, both of which they attributed to our master builder MACFARAMUS. They decided (how we will never know), that the artefacts were scale models of a pyramid and the partial wheel from a chariot. It is these that you have to create as solid models from swept primitives. Activity 19: Two swept primitive models designed by MACFARAMUS. These two models have to be created from closed polylines. The dimensions taken by the site engineers were not complete and only the basic sizes have been given. You have to use your own discretion when drawing the two outlines. The procedure for both models is: 1 Open your template file as normal 2 Draw the outline of the model as a closed polyline, both with UCS BASE, layer MODEL and with the lower right viewport active 3 Extrude the pyramid outline for a height of 150 and a taper angle of 10 4 Revolve the wheel outline about the X or Y axis dependent on how the original outline was drawn. The partial angle of revolution is to be 270 degrees 5 Centre the models in the viewports 6 Note: I have displayed both models on the one sheet of paper with: a) pyramid: 3D and front views b) wheel: two 3D views, from above and from below 204 Modelling with AutoCAD 2002 modelling with AutoCAD.qxd 17/06/2002 15:41 Page 204 Boolean operations and composite solids The basic and swept solids which have been created are called primitives and are the ‘basic tools’ for solid modelling. With these primitives the user can create composite solids, so called because they are ‘composed’ of two or more solid primitives, i.e. a) primitive: a box, wedge, cylinder, extrusion, etc. b) composite: a solid made from two or more primitives. Composite solids are created from primitives using the three Boolean operations of union, subtraction and intersection. Figure 30.1 demonstrates these operations with two primitives: a) a box b) a cylinder ‘penetrating’ the box Chapter 30 Figure 30.1 The three BOOLEAN operations. modelling with AutoCAD.qxd 17/06/2002 15:41 Page 205 Union 1 This operation involves ‘joining’ two or more primitives to form a single composite, the user selecting all objects to be unioned 2 The operation can be considered similar to welding two or more components together. Subtraction 1 This involves removing one or more solids from another solid thereby creating the composite. The user selects: a) the source solid b) the solids to be subtracted from the source solid 2 The result of a subtraction operation can be likened to a drilled hole, i.e. if the cylinder is subtracted from the box, a hole will obtained in the box. 3 Note: the source solid is generally ‘the larger solid’ i.e. you cannot normally take a large solid from a small solid Intersection 1 This operation gives a composite solid from other solids which have a common volume, the user selecting all objects which have to be intersected 2 The box/cylinder illustration of the intersection operation gives a ‘disc shape’ or ‘hole’ i.e. if the box and cylinder are intersected, the common volume is the disc shape. Creating a composite solid from primitives There is no ‘correct or ideal’ method of creating a composite, i.e. the Boolean operations selected by one user may be different from those selected by another user, but the final composite may be the same. To demonstrate this, we will create an L-shaped component by three different methods, so: 1 Open your A3SOL template file refer to Fig. 30.2 and: a) enter paper space b) erase any text and the four viewports c) with layer VP current create a single viewport with: i) first point: pick to suit in lower left corner area ii) other corner: enter @360,220 d) return to model space, UCS BASE, layer MODEL e) set a SE Isometric viewpoint 2 Create two box primitives: a) corner: 0,0,0 b) corner: 100,100,100 cube option length: –60 length: 100 width: –100 colour: red height: –70 colour: blue 3 Create another two box primitives: a) corner: 125,125,0 b) corner: 125,125,30 length: 100 length: 40 width: 100 width: 100 height: 30 height: 70 colour: red colour: blue 206 Modelling with AutoCAD 2002 modelling with AutoCAD.qxd 17/06/2002 15:41 Page 206 4 Restore UCS FRONT and draw a 2D polyline shape: start pt: 500,250 next pt: @100,0 next pt: @0,30 next pt: @–60,0 next pt: @0,70 next pt: @–40,0 next pt: close 5 Restore UCS BASE and zoom centre about 100,250,0 at 400 mag. 6 From the menu bar select Modify-Solids Editing-Subtract and: prompt Select solids and regions to subtract from Select objects respond pick the left red box then right-click prompt Select solids and regions to subtract Select objects respond pick the left blue box then right-click and the blue box is subtracted from the red box 7 Menu bar with Modify-Solids Editing-Union and: prompt Select objects respond pick the middle red and blue boxes then right-click and the two boxes will be unioned 8 Restore UCS FRONT and: a) select the EXTRUDE icon from the Solids toolbar b) pick the L shaped polyline then right-click c) enter an extruded height of –100 with 0 taper d) the L-shape polyline is extruded into a composite Boolean operations and composite solids 207 Figure 30.2 Creating the same composite by three different methods. modelling with AutoCAD.qxd 17/06/2002 15:41 Page 207 9 Task a) Hide the models – all the same b) Gouraud shade the models and note colour effect between the union and subtraction composites – any comment? c) Return to 2D wireframe representation d) Menu bar with Tools-Inquiry-Region/Mass Properties and: prompt Select objects respond pick left composite then right-click and AutoCAD Text Window with: Mass: 580000.00 Volume: 580000.00 Bounding box, Centroid etc. enter N <R> in response to ‘Write analysis to file’ prompt d) Repeat the MASSPROP command and select the middle and right composites – same mass and volume? 10 Questions a) Why are the mass and volume the same? Answer: AutoCAD 2002 assumes a density value of 1 and does not support different material densities b) Is the volume of 580000 correct for the L shape? c) What are the volume units? 11 Now that we have investigated the Boolean operations, we will create some composite solid models which (I hole) will be interesting. Summary 1 There are three Boolean operations – union, subtraction and intersection 2 The three operations can be activated: a) from the menu bar with Modify-Solids Editing b) in icon form from the Solids Editing toolbar c) by entering the command from the keyboard. 3 The Boolean operations are derived from Boolean Algebra (set theory) and are essential for the creation of solid composites from primitives. 208 Modelling with AutoCAD 2002 modelling with AutoCAD.qxd 17/06/2002 15:41 Page 208 Composite model 1 – a machine support In this exercise we will create a composite solid from the box, wedge and cylinder primitives using the three Boolean operations. Once created, we will dimension the model using viewport specific layers. The exercise is quite simple and you should have no difficulty in following the various steps in the model construction. Try and work out why the various entries are given – do not just accept them. 1 Open your A3SOL template file with normal settings and display the Solids, Solids Editing and other toolbars to suit. 2 Refer to Fig. 31.1 which displays only the 3D viewport of the model at various stages of its construction Chapter 31 Figure 31.1 Creation of composite model 1 – a machine support. modelling with AutoCAD.qxd 17/06/2002 15:41 Page 209 3 In each viewport, zoom-extents then zoom to 1.5 scale 4 With the 3D viewport active, use the BOX icon to create two primitives as fig(a) with: a) corner: 0,0,0 b) corner: 100,120,25 length: 100 length: –100 width: 150 width: –90 height: 25 height: 60 colour: red colour: blue 5 Create a cylinder on top of the blue box with: a) centre: 50,30,85 b) radius: 50 c) height/other end: enter C <R> then @0,90,0 <R> d) colour: green 6 Create a wedge with: a) corner: 0,120,85 b) length: 70; width: 100; height: 70 c) colour: magenta 7 Rotate (2D rotate) the magenta wedge: a) about the point: 0,120,85 b) by: –90 degrees to give fig(b) 8 Select the INTERSECTION icon from the Solids Editing toolbar and: prompt Select objects respond pick the green cylinder and magenta wedge then right-click 9 Select the UNION icon from the Solids Editing toolbar and: prompt Select objects respond pick the red and blue boxes and the intersected wedge/cylinder then right-click 10 The model now appears as fig(c) 11 Refer to fig(c) and menu bar with Tools-New UCS-3 Point and set a new UCS with: a) origin: MIDpoint icon and pick line 12 b) X axis: ENDpoint icon and pick pt2 c) Y axis: QUADrant icon and pick pt3 on curve 12 The UCS icon will move and align itself on the sloped surface Note: if icon does not move, menu bar with View-Display-UCS Icon and ensure that On and Origin are ticked 13 Save this UCS position as SLOPE 14 Create a cylinder with: a) centre: 0,35,0 b) radius: 18 c) height: –100 d) colour: number 54 – use the CHPROP command 15 Select the SUBTRACT icon from the Solids Editing toolbar and: prompt Select solids and regions to subtract from Select objects respond pick the composite model then right-click prompt Select solids or regions to subtract Select objects respond pick the cylinder then right-click – fig(d) 210 Modelling with AutoCAD 2002 modelling with AutoCAD.qxd 17/06/2002 15:41 Page 210 16 Restore UCS BASE 17 Create a cylinder with: a) centre: 20,15,0 b) radius: 9 c) height: 25 d) colour: number 174 18 Multiple copy the cylinder: a) from: 20,15 b) by: @60,0 and by: @30,120 20 Using the SUBTRACT icon: a) select the original composite then right-click b) pick the three cylinders then right-click 21 The model is now complete and is displayed in fig(e) without hide and in fig(f) with hide. 22 Select the Model tab and Gouraud shade the model, then use the 3D orbit command to rotate the shaded model 23 Restore the model to 2D wireframe representation, then make the MVLAY1 tab active 24 At this stage save the composite as MODR2002\MACHSUPP Making the viewport specific layers The MVLAY1 tab screen displays the model in a four viewport configuration and we now want to add some dimensions. These dimensions must be added on viewport specific layers and these layers must now be created. 1 At the command line enter VPLAYER <R> and: prompt Enter an option [?/Freeze/Thaw/Reset/Newfrz/Vpvisdflt] enter N <R> – the Newfrz (new viewport freeze) option prompt Enter name(s) of new layers frozen in all viewports enter DIMTL,DIMTR,DIMBR <R> prompt Enter an option [?/Freeze/Thaw/ respond right-click – as finished with command 2 The command line entry VPLAYER is to activate viewport layer 3 Make the top left viewport active and menu bar with Format-Layer and: prompt Layer Properties Manager dialogue box note three new layers – DIMBR, DIMTL, DIMTR with: i) Frozen in current viewport – blue icon ii) Frozen in new viewport – blue icon respond 1. activate Show Details 2. pick DIMTL (highlights) and note details – Freeze in current viewport is on (tick) 3. pick blue icon Freeze in active viewport to Thaw the layer and the tick is removed from Freeze in current viewport details list 4. pick OK 4 With the top right viewport active, Format-Layer and: a) pick layer DIMTR b) toggle the blue Freeze in current viewport icon to yellow to Thaw layer DIMTR in the top right viewport c) pick OK Composite model 1 – a machine support 211 modelling with AutoCAD.qxd 17/06/2002 15:41 Page 211 5 With lower right viewport active, Format-Layer and: a) pick layer DIMBR b) toggle Freeze icon in current viewport from blue to yellow, i.e. from Frozen to Thaw to Thaw layer DIMBR in the lower right viewport c) pick OK 6 What has been achieved in this section? a) three new viewport specific layers have been made b) these layers have been named DIMTL for the top left viewport, DIMTR for the top right viewport and DIMBR for the bottom left viewport c) the three layers were originally created : i) frozen in new viewports ii) currently frozen in all viewports d) each layer was currently thawed in a specific viewport, e.g. layer DIMTL is currently thawed in the top left viewport but is currently frozen in the other three viewports. Layers DIMTR and DIMBR are currently frozen in the top left viewport. 7 Before adding the dimensions, change the colour of the three new layers (DIMTL, DIMTR, DIMBR) to magenta using the Layer Properties Manger dialogue box. Adding the dimensions 1 Before the dimensions are added to the model, menu bar with Dimension-Style and using the Dimension Style Manager dialogue box: a) 3DSTD the current (and only) style? b) pick Modify c) pick the Fit tab d) Alter Scale for Features: Use overall scale of 2 e) pick OK to return to Dimension Style Manager dialogue box f) pick Close 2 This will scale all the dimension parameters by 2 3 Make the lower right viewport active and: a) restore UCS BASE b) make layer DIMBR current c) refer to Fig. 31.2 4 With Dimension-Linear from the menu bar, or with the LINEAR dimension icon from the Dimensions toolbar, add: a) the horizontal dimension b) the four vertical dimensions using the baseline option 5 With the top right viewport active: a) restore UCS FRONT b) make layer DIMTR current c) add the two linear dimensions 6 Make the top left viewport active and: a) restore UCS RIGHT b) make layer DIMTL current c) add the six dimensions 7 The composite model is now complete with dimensions added and can be plotted with the layer VP frozen for effect – Fig. 31.2 8 These dimension additions do not need to be saved. 212 Modelling with AutoCAD 2002 modelling with AutoCAD.qxd 17/06/2002 15:41 Page 212 [...]... model space with viewport B active Figure 32.2 Steps in the creation of the backing plate composite 215 modelling with AutoCAD. qxd 216 17/06 /2002 15:41 Page 216 Modelling with AutoCAD 2002 Creating the extrusion 1 Using the polyline icon from the Draw toolbar, create a single polyline from line and arc segments with the following entries: Start point 0,0 Next point @27,0 Next point Arc option, with endpoint... fig(f) and the four viewport layout should be displayed as Fig 32.3 16 Save the model layout as MODR2002\BACKPLT 17 Shade and use the 3D orbit command in the 3D viewport, then return the model to wireframe representation 217 modelling with AutoCAD. qxd 2 18 17/06 /2002 15:41 Page 2 18 Modelling with AutoCAD 2002 Figure 32.3 Complete solid model composite of backing plate Investigating the model 1 Display... square box ‘front’, distances: 10 7 Fillet the green cylinder ‘right side’ with radius 10 8 Save the composite as MODR2002\MODCOMP 227 modelling with AutoCAD. qxd 17/06 /2002 15:41 Page 2 28 Chapter 35 Solids editing AutoCAD 2002 allows solid primitives and composites to be edited, the commands being activated from the: a) menu bar with Modify-Solids Editing b) Solids Editing toolbar The editing facilities... and X modelling with AutoCAD. qxd 230 18/ 06 /2002 11:23 Page 230 Modelling with AutoCAD 2002 11 The selected top surface will be tapered as fig(e) 12 Menu bar with Modify-Solid Editing-Rotate Faces and: prompt Select faces or [Undo/Remove] respond pick any pt7 on face indicated then right-click/enter prompt Specify an axis point or [Axis by object respond Endpoint icon and pick pt8 prompt Specify... easily be removed from the ‘selection’ with the ‘R’ entry 3 The solids editing command allows the user repetitive options, i.e when one option has been completed, the command is still active The UNDO option is very useful 4 The solids editing command is exited with two X or ESC modelling with AutoCAD. qxd 232 18/ 06 /2002 11:24 Page 232 Modelling with AutoCAD 2002 Solids editing example 3 1 Open your... The top of the cylinder is chamfered with the entered values 223 modelling with AutoCAD. qxd 224 17/06 /2002 15:41 Page 224 Modelling with AutoCAD 2002 7 Select the FILLET icon and: prompt Select first object respond pick bottom circle of cylinder prompt Enter fillet radius and enter: 25 prompt Select an edge respond right-click as bottom edge already selected 8 The cylinder is filleted at the base... PROPERTIES icon and: prompt Select objects respond pick the composite then right-click prompt AutoCAD Text Window with Mass = 982 83 .83 and other ‘technical’ information about the model enter N i.e do not write to file More on this later This completes the exercise on the extruded model modelling with AutoCAD. qxd 17/06 /2002 15:41 Page 219 Chapter 33 Composite model 3 – a flange and pipe This exercise will... Erase the composite on the screen and ensure UCS BASE, layer MODEL and lower left viewport active Refer to Fig 34.3 Figure 34.3 Practical use for chamfer/fillet 225 modelling with AutoCAD. qxd 226 17/06 /2002 15:41 Page 226 Modelling with AutoCAD 2002 2 Create the following three box primitives: box1 box2 box3 corner 0,0,0 0,0,100 10,100,10 length 100 10 90 width 100 100 –10 height 10 90 90 3 Union the three... 2 With Model tab active, layer MODEL current, UCS BASE create the following: a) Box: corner at 0,0,0 with cube of length 200 and colour red b) Cone: centre at 0,100,100; radius: 80 ; Apex at @300,0 and colour: green c) Subtract the green cone from the red box d) Pan to suit and alter the viewpoint with to suit – fig(a) Figure 35.2 Solids editing example 2 – 3D viewport without hide modelling with AutoCAD. qxd... operation? 8 Make the lower right viewport active and restore UCS BASE 9 With the POLYLINE icon from the Draw toolbar, draw a continuous closed polyline with the following entries: Start point: 0,–30 Next point: @0,–10 Next point: @10,0 Next point: Arc option with endpoint: @10,–10 Next point: Line option with endpoint: @0,–50 Next point: @30,0 Next point: @0,70 Next point: close option modelling with AutoCAD. qxd . essential for the creation of solid composites from primitives. 2 08 Modelling with AutoCAD 2002 modelling with AutoCAD. qxd 17/06 /2002 15:41 Page 2 08 Composite model 1 – a machine support In this exercise. complete with dimensions added and can be plotted with the layer VP frozen for effect – Fig. 31.2 8 These dimension additions do not need to be saved. 212 Modelling with AutoCAD 2002 modelling with AutoCAD. qxd. cylinder then right-click – fig(d) 210 Modelling with AutoCAD 2002 modelling with AutoCAD. qxd 17/06 /2002 15:41 Page 210 16 Restore UCS BASE 17 Create a cylinder with: a) centre: 20,15,0 b) radius: